Cells already present in the eye are able to generate a new lens—if we let them.

Cataracts—the clouding of the lens in our eyes—are the leading cause of blindness in the world. Though we often associate them with the elderly, they're also a major cause of vision loss in infants, especially in the developing world. In either case, they are dealt with surgically, by removing the entire lens and replacing it with either a transplanted lens or an artificial one.

More than twenty million people undergo this surgery annually, but it often comes with a host of complications, and children in particular usually still need glasses afterward. But now some researchers have shown that it's possible to skip the replacement lens and get stem cells to repair the damage, a procedure that results in fewer complications.

Researchers in China noticed that the eye contains lens epithelial stem/progenitor cells (LECs) that continue to divide, even in forty-year-old adults. Injury can stimulate them to grow into three-dimensional, transparent, light refracting, lens-like structures. Rather than using artificial lenses, these researchers thought, maybe they could get infants to regrow their own new lenses.

First they tried their new procedure in rabbits and baby macaques. Normally, the surgical procedure involves making a large wound and removing most of the LECs with the cataract, as has traditionally been done in order to insert the artificial lens. But if the LECs hold the very key to regenerating a functional lens, this might not be the best way to go about things.

So instead, they made a small wound that preserved the LECs that were already in place while removing only the clouded native lens. By seven weeks, the eyes of the animals that had surgery looked the same as those that hadn’t.

Next they tried their procedure in twelve infants—or, as they helpfully note, twenty-four eyes. Their results in terms of visual acuity six months after surgery were as good as those achieved with the traditional method. But the artificial implants almost always result in complications that further restrict vision—ironically, these problems are due to the abnormal growth of the few residual LECs.

This new, minimally invasive technique reduced the most common complication twenty-fold—only one out of their twelve patients ended up with it, compared to 24 out of 25 control infants who got the traditional procedure at the same time.

Adult cataracts are not the same as the pediatric variety, but since adult LECs have regenerative capacity, perhaps this procedure could be modified to deal with age-related cataracts as well. This first instance of human lens regeneration could well be a step on the path toward using endogenous stem cells to repair other tissues that need regeneration.